On Fri, Jul 23, 2021 at 8:30 AM Al Viro [off-list ref] wrote:

On Fri, Jul 23, 2021 at 07:03:02AM +0200, Christoph Hellwig wrote:

quoted

On Thu, Jul 22, 2021 at 11:23:38PM +0300, Boris Pismenny wrote:

quoted

quoted

This routine, like other changes in this file, replicates the logic in
memcpy_to_page. The only difference is that "ddp" avoids copies when the
copy source and destinations buffers are one and the same.

quoted

Now why can't we just make that change to the generic routine?

Doable... replace memcpy(base, addr + off, len) with
        base != addr + off && memcpy(base, addr + off, len)
in _copy_to_iter() and be done with that...

Guys,

AFAIR we did the adding ddp_ prefix exercise to the copy functions call chain

ddp_hash_and_copy_to_iter
-> ddp_copy_to_iter
-> _ddp_copy_to_iter
-> ddp_memcpy_to_page

to address feedback given on earlier versions of the series. So let's
decide please.. are we all set to remove the ddp_ prefixed calls and just
plant the new check (plus a nice comment!) as Al suggested?

re the comments given on ddp_memcpy_to_page, upstream move
to just call memcpy, so we need not have it anyway, will be fixed in v6
if we remain with ddp_ call chain or becomes irrelevant if we drop it.

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